The purpose of these studies is to accurately document demographic environmental and geographic differentials in the prevalence of major neurologic disorders by survey of geographically defined populations and cerebrovascular disease. Using information from the two National Health and Nutrition Examination Surveys (NHANES I and II), probability sample surveys of the US population, detailed information was utilized concerning self-reported sleep disorders, neck pain, and other neurologic problems. Overall, 39% of Americans reported sleep problems. These were more frequent in women and increased with advancing age, poor health, depression, and chronic disease. Neck pain lasting at least two weeks was reported by 8.2% of surveyed Americans, and was more common in women; 5% of those with neck pain had surgery for this problem. The prevalence of neck pain increased with age until a plateau in those aged in the 60s. Both sleep difficulties and neck pain occurred with substantial frequency in this country. Of the more than 10,000 respondents, 9.8% reported migraine, 0.49% persons reported Parkinson's disease, 0.22% multiple sclerosis, 0.69% epilepsy, 2.3% transient ischemic attacks, and 1.3% strokes. In 1993, the World Health Organization requested the participation of Dr. Gustavo C. Roman, then Chief, NEB, in a team of scientist which traveled to Cuba to investigate an outbreak of optic and peripheral neuropathy in the island. As of January 1994, more than 50,000 cases were reported making this one of the largest epidemics of neurologic disease on record